How Long Can You Leave Resin in the 3D Printer Vat?

Marcello De Lio

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Close up of an SLA 3D printer printing a sphere with geometric supports

Changing the vat in a resin 3D printer is a tedious process. I often leave resin for one or two days without any issues. But just how long can you leave resin in the 3D printer vat?

Resin does separate over time, which impacts the quality of your 3D prints.

Here’s everything you need to know.

How Long Can You Leave Resin in the 3D Printer Vat?

Grey objects on the build plate of a msla printer with Resin in the 3D Printer Vat

You can leave resin in the 3D printer vat for three to four months if it is protected from UV light, heat, and dust. Exposure to UV light reduces the lifespan of your UV-cured resin.

I recommend leaving the resin in the vat of your resin printer for no longer than two months. While resin can last longer under ideal conditions, I find resin begins to degrade in quality after two months.

A resin 3D printer in a cool, dark basement lasts longer in the vat than a 3D printer in a hot, humid workspace.

Resin separates when left in the vat, so you’ll want to stir it before beginning your next print.

There’s nothing wrong with stirring resin in the vat. However, you’ll need to be careful not to break the FEP film.

Use the plastic scrapper that comes with your resin 3D printer to stir the UV resin. Avoid using a metal scrapper that can damage the FEP film.

Editor’s Note

I recommend using a PTFE or silicone spray on the FEP film to prevent cured resin from sticking. The PTFE spray makes it easier to clean the vat and reduces failed 3D prints caused by cured resin interfering with the print.

Can I Leave Resin in the Vat Between Prints?

A resin 3d printer with two yellow objects on the build plate and resin left in the vat

You can leave resin in the vat between prints without affecting print quality.

Below are some recommendations to maintain the quality of your prints and the longevity of your resin and printer.

  • Duration: Most manufacturers suggest that resin shouldn’t be left in the vat for over two months. Resin deteriorates after two months, affecting print quality.
  • Stirring: Before your next print, gently stir the resin to keep its composition consistent. Resin that has been sitting separates or settles.
  • Protection: Always shield the resin from UV light to prevent premature curing. Use the printer’s UV protective cover or store the vat in a cool, dark place.

It’s safe to leave the resin in the vat with UV protection. Just remember to stir before use and check for any signs of degradation.

Can You Leave Resin Overnight?

You can leave resin overnight in your resin 3D printer. Leaving resin overnight is convenient, especially if you plan to resume printing the next day.

However, keep the vat protected from UV light, heat, and dust to prevent accidental curing or degradation of the resin.

Before starting a new print, gently stir the resin to ensure consistency.

By following these guidelines, your resin should remain in a usable state overnight without significant issues. Remember to always handle resin with care and in a well-ventilated area.

How Long Does UV Cured Resin Last?

A clear orange resin 3D printed dragon on a platform with a tech background

Most UV-cured resins used in 3D printing have a shelf life of one year. You may be able to use the resin without issues after one year, but the quality will begin to lessen.

In my experience, 3D printing resins last much longer than one year. I’ve printed three-year-old resins without issues. However, I always try to purchase resin as needed to avoid issues with printing old resin.

Always store resin in the original bottle with the lid tightly sealed. UV resin bottles block UV light to prevent accidental curing. Make sure you swirl your resin bottle before pouring it to ensure the resin is adequately mixed.

Ensure you filter used resin before pouring it back into the bottle to prevent cured bits of resin from entering your next print. Small bits of cured resin interfere with the print process and create print defects and failed prints.

Editor’s Note

Always wear protective equipment like gloves and eyewear when handling uncured resin, as uncured UV resin is toxic.

What Can I Do With Leftover 3D UV Resin?

When you’re left with excess UV resin from your 3D printing projects, here are some environmentally responsible and practical options for what you can do with it:

  • Leave in the Vat:
    • You can leave resin in the vat if you will print in a few days.
  • Storage for Future Use:
    • Store leftover resin in an airtight container with UV protection.
    • Store in a cool, dark place away from UV light.
    • Label containers with dates to use the oldest resin first.
  • Cure and Dispose:
    • Spread resin on a disposable surface and expose it to UV light to cure.
    • Once hardened, dispose of leftover UV resin as solid waste.
  • Make New Objects:
    • Use spare resin to create small test prints or samples.
    • Experiment with new printing techniques or settings.

Can You Reuse 3D Printer Resin?

Yes, you can reuse uncured UV resin. You should always filter resin before reusing it to prevent fragments of cured resin from entering the bottle.

Article by

Marcello De Lio

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